Present methods of commercial steel production generally call for forming giant steel ingots from an initial melt by pouring the liquid metal into a mold, and later utilizing these ingots during subsequent manufacturing operations. It is generally desired that these ingots be formed substantially free of large voids.
It is well known in the steel industry that the undesired large voids appear in the ingot if premature solidification takes place in the region of the upper edges of the mold while the mold is still being filled or while the metal in the center of the mold is still molten. This premature solidification must therefore be prevented if substantially void-free ingots are to be cast. The typical method of preventing this solidification is to apply a liner of suitable insulation, generally available in the industry under the names Hot-Top and Riser, to the inside surface of the mold at its upper end. The insulation acts to prevent heat loss through the mold at its upper end, thereby assuring that the melt will not prematurely freeze on the mold. The preferred manner of attaching the insulation to the mold is to fasten it on by means of nail-like fasteners, with the point of the fastener penetrating the insulation and fixing itself in the wall of the mold and the head or shank of the fastener engaging the washer which in turn engages the insulation liner and holds it firmly against the mold.
Unfortunately, there have been a number of difficulties associated with this fastening technique. First, the heavy cast iron molds used in casting the ingots have proven more impervious to fastener penetration than ordinary steel. As a result, very high power impact drivers have been required to set the fasteners. Second, the very nature of the fastening job has dictated that the impact drivers be highly mobile and light in weight so as to facilitate fastening. And third, it has been found to be highly preferable to deploy the fastener with a washer spaced between the head of the fastener and the insulation liner so as to prevent the fastener from excessively penetrating the insulation.
To date, only explosive-activated impact drivers have come close to satisfying these requirements. Unfortunately, these devices are also relatively slow in operation, expensive, dangerous to operate, and suffer from substantial noise and recoil problems. In addition, these devices require that the operator manually position a preassembled washer/fastener in the front end of the barrel of the gun one at a time and the explosive charge above the fastener. This manual loading of the washer/fastener and the explosive charge slows down the operation of the tool. Furthermore the lack of an adequate handle and trigger extension has added significant problems to utilizing these tools around the giant (e.g. 5'.times.4'.times.10') cast iron molds previously described, e.g. operators have been required to work in an awkward position when attaching the insulation to the mold.
As a result, one of the objects of the present invention is to provide a device for attaching insulation to cast iron molds which is substantially free of the problems facing explosive-activated impact tools.
Another object is to provide means for adapting a pneumatic fastener driver of the type shown in U.S. Pat. No. 4,040,554 for attaching insulation to cast iron molds.
Yet another object is to provide means for automatically deploying a washer with the fastener as part of the normal operation of the tool, without the operator having to manually position a washer/fastener for each fastening operation.
Still another object is to produce a fastening device which is relatively light in weight and has a high degree of mobility.
And another object is to provide a fastening tool which has a handle and trigger extension for using the tool in hard-to-reach locations.